The goal of this research is to determine the transcription pattern and regulation of the genes of the R plasmid 538-1. In vivo experiments are aimed at determining the regions of transcription and effect of heavy metals (Hg ions) and mutations effecting the level of transcription of transfer genes. The nucleotide sequence of several plasmid promoters including those for chloramphenicol and streptomycin resistance is being determined. In vitro transcription experiments of restriction fragments carrying these promoters will be carried out.